NEW YORK, N.Y., March 10, 2004 -- Post-menopausal breast cancer
patients who switched from tamoxifen to Aromasin (exemestane tablets) had a significantly
reduced chance of recurrence and increased disease-free survival
compared to patients who remained on tamoxifen, according to new
data published today in the New England Journal of Medicine.

The Intergroup Exemestane Study (IES) involved over 4,700
post-menopausal women in 37 countries with breast cancer who were
followed for an average of 31 months. According to a current
treatment paradigm, post-menopausal women with estrogen-receptor
positive breast cancer receive tamoxifen for five years after
surgery to prevent recurrence.

The IES study demonstrated that patients who switched to
Aromasin after two or three years of taking tamoxifen were more
likely to remain cancer free than those who continued on tamoxifen.
Patients receiving Aromasin experienced a 32 percent reduction in
the risk of recurrence of the disease at three years, as compared
to those continuing on tamoxifen. This reduction includes fewer
local and distant tumors as well as new cancer in the other
breast.

"Results from this study are important since many patients
taking tamoxifen alone relapse within five years of diagnosis,"
said Dr. Charles Coombes, lead investigator and Head of Department
of Cancer Medicine, Imperial College School of Medicine in England.
"This is the first large multi-center trial to challenge the
current concept of five years monotherapy with endocrine agents
after surgical treatment of primary breast cancer. It shows that
patients switched to Aromasin experienced statistically significant
clinical benefit and longer disease-free survival."

The independent group monitoring the IES study recommended
releasing these findings early as a result of the strength of these
data.

"These are important findings for the many women afflicted with
breast cancer worldwide," said Dr. Joseph Feczko, president of
Worldwide Development at Pfizer. "These data provide women with a
new treatment option that can provide a real disease-free survival
benefit."

In the double-blind trial, after two-to-three years of adjuvant
(after surgery) tamoxifen therapy, patients were randomized to
receive either Aromasin (25 mg) or to continue on tamoxifen (20 mg)
daily.

"This large global study had significant results in terms of
reduction in the risk of recurrence of breast cancer as well as the
occurrence of new cancer in the other breast," said Dr. Stephen
Jones, medical director at U.S. Oncology Research. "I believe the
importance of this study is that it could alter practice. Standard
practice has been to give tamoxifen for five years, however this
study shows that patients will have better outcomes when they
receive tamoxifen for two-to-three years then switch to
exemestane." Aromasin was generally well tolerated. Continuation of
tamoxifen therapy was associated with a greater incidence of
endometrial cancer, blood clots, hot flashes, vaginal bleeding, and
muscle cramps. Joint pain and diarrhea were reported more
frequently in the Aromasin group.

The International Collaborative Cancer Group under the auspices
of the Breast International Group coordinated the IES study, which
was sponsored by Pfizer.